diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2012-03-01 02:04:32 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-03-03 04:22:11 +0400 |
| commit | 371f3b49f2cb1a8b6ac09b6b108841ca92349eb1 (patch) | |
| tree | 65bb502f1a543963484e985772050a0897baabf8 | |
| parent | 2a5be8783e0016d15e7907ddd212b2c312e196eb (diff) | |
| download | linux-371f3b49f2cb1a8b6ac09b6b108841ca92349eb1.tar.xz | |
usb/core: remove "always" from usb_unlink_urb() kernel doc entry
The kernel doc entry for usb_unlink_urb() contains the phrase "This
request is always asynchronous.". The "always" leads to the assumption
that the ->complete() callback is not called from within
usb_unlink_urb(). This is not true. The HCD is allowed to call the
->complete() from within ->urb_dequeue() if it is appropriate for the
hardware.
This patch updates the kernel doc so usb-device driver authors make sure
to drop all locks (and make sure it is okay to drop them) which are
acquired by the complete callback before calling usb_unlink_urb().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/core/urb.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c index f4f20c7b7765..7239a73c1b8c 100644 --- a/drivers/usb/core/urb.c +++ b/drivers/usb/core/urb.c @@ -527,10 +527,13 @@ EXPORT_SYMBOL_GPL(usb_submit_urb); * a driver's I/O routines to insure that all URB-related activity has * completed before it returns. * - * This request is always asynchronous. Success is indicated by - * returning -EINPROGRESS, at which time the URB will probably not yet - * have been given back to the device driver. When it is eventually - * called, the completion function will see @urb->status == -ECONNRESET. + * This request is asynchronous, however the HCD might call the ->complete() + * callback during unlink. Therefore when drivers call usb_unlink_urb(), they + * must not hold any locks that may be taken by the completion function. + * Success is indicated by returning -EINPROGRESS, at which time the URB will + * probably not yet have been given back to the device driver. When it is + * eventually called, the completion function will see @urb->status == + * -ECONNRESET. * Failure is indicated by usb_unlink_urb() returning any other value. * Unlinking will fail when @urb is not currently "linked" (i.e., it was * never submitted, or it was unlinked before, or the hardware is already |